Speaker unit



July 10, 1928 A 1676mm 0. 3n DRAKE SPEAKER UNIT Filed. July 18', 1927 3ZZ 5- 2 JNVENTOR BY GHQ 63. Dmafi.

60a (mm A TTORNEY Patented July 10, 1928.

OTTO S DRAKE, OF NEWBURGH, NEW YORK.

SPEAKER UNIT.

Application filed July 18, 1927. Serial No. 206,472.

This invention relates to a magneticunit of that class which is employedin loud speakers, such are used in the cone type of radio horn, but theinvention may be put to many 6 other. uses init-s present form, and byminor changes in design-or mounting tomany other uses.

While there have been many instruments of this same kind made, they havehad several disadvantages and have been faulty in construction anddesign and inthe method employed for adjusting the air gap and the polepieces, and while some of them provide means for adjusting the air gap,said means is of such a crude nature that in locking the adjustable,parts in place, the line adjustment is lost, and in fact it isimpossible to make a fine adjustment of one or two thousandths of aninch, which is of vital importance for- 'the best results in instrumentsof this class.

' In the design herewith shown, it is possible not only to make and holda very fine adjustment of the pole pieces with respect to each other,but also to further adjust the armature with respect to the pole pieces,and to lock said adjustments without disturbing the same.

Another object of the invention is to conslruct an instrument of thiskind that shall be simple, strong, contain few parts and be easy ofmanufacture.

\Vith these and other objects in view, my invention consists in certainconsl motion and combination of parts as will hereinafter be 35 .l'ullydescribed and claimed, and illustrated in the accompanying drawingswhich form a part hereof and in which like 'iigures of reference referto corresponding parts in all of the views, and it is fully understoodthat slight changes may be made without dcparting from the spirit of theinvention.

'lhedevice is known as the balanced type, where the translating coil isin two parts, one

- hall on each side of. the armature which is securedncar its center andoperates between two sols of air gaps, thus producing a very sensitiveinstrument, also the driver pin which lrausn'iilsthe movcnu'ul' l'romthe armalure lo the cone, does so with a straight line and compoundmovement.

In the drawings:

Figure l is a top plan view of the iuslrumcnl... with lhc exception ofthe cone and bracket or other means for mounting the 55 same, which isnot shown.

Figure 2 is an end view of the same, with the driver pin partly cut oil.

Figure 3 is a cross sectional view taken on the line A-A of Figurel.

' Figure 4 is a transverse view of the same with one of the coil spacersand one offthe' permanent pole pieces removed.

Figure 5 shows an exploded view of the several parts making up the unit.

Figure 6 is a top plan View of one of the permanent pole pieces.

Figure 7 shows the method employed in assembling the armature to thearmature bar.

Referring to the drawings It is to be understood that while the usualhorse-shoe magnet 10, is shown, that this permanent magnet may be of anydesired shape or form, of one piece, or' built up. i

To the ends thereof, oneto the upper side and the other to the lowerside are attached by the screws 11 and nuts 12, the two permanent polepieces 13 of suitable material, which are formed with the notches .14,and the secrew holes 15 and 16..

Secured to said permanent pole pieces 13 by the screws 17 through theholes 16 and at right angles therewith are the brass coil spacers 18,which are L-shaped, and which are provided with the alined bearings 19and the slots 37, and the coil spacer pins 20.

The armature assembly, comprising the two alined armature adjustingplugs 21, which are secured to=the ends of the armature bar 22, ofsuitable material such as phosphor bronze, by brazing or otherwise se- 9curing to said plugs; and the armature 23 being formed with the notches24 (see Fig. f4) near its center which areadapted to reccive the lockingtongues 25 which have been formed on the bar 22 adjacent to.the hole,and which are pressed down into said notches "24' holding the armaturerigid to the bar 22 and at right angles therewith.

The above assembly is mounted with the plugs 21 in the bearings providedin the brass coil spacers 18 and are held therein in a locked posiliouby one of the screws 17 which isthreaded into the part 26 of said spacerlb, and passes through a clearance hole in the purl 27 of the samespacer which is divided into these two parts by the saw cut 37communicating with the bearin lJ, to rovide agrip on the plug 21 in saidhe'aring, and in this way the lugs 21 maybe turned in said bearings 19,y the use of a spanner wrench (not-shown) which will enter thetransverse holes 28 in said plugs 21, and in this manner the armature23, may not only be rocked to adjust the air gaps but also adjustedlengtliwise', and when'so adjusted, it is locked by tightening thescrews 17. v

The adjustable pole pieces 29 are made up of laminations' U-shaped andriveted together to form said pole pieces '29, which are mounted asfollows. The permanent pole piece 13 is secured in abutting ,relation tothe brass coil spacer 18 by the screws 30, passing through said spacer18 and threaded into the pole pieces 13; which leaves the notches 14 inan alined and parallel relation with the armature 23, and as saidnotches 14 are slightly narrower than the thickness of the pole pieces29, so that said pole pieces 29 having been placed with their legs insaid notches 14, and slid in until their ends give the proper air gap,

the screws 30 are tightened which will draw I the parts 18.-and 13together to press on and hold said adjustable pole pieces 29 in place,and by looseiiingsaid screws 30, the air gap may be adjusted by tappingin on the pole pieces29 to lessen the gap, or by pulling out to widenthe gap, and again clamping by the crew 30, and in this manner not onlyfine djustment is gotten, but said adjustment can not get out. ofadjustment during the locking of the parts.

The coils 31 are mounted within the space formed by the permanent polepieces 13 and the brass spacers 18, and surround the armature 23, andare spaced apart by the pins 20, and their leads 32 may be brought outto any suitable binding posts on the frame (not shown).

For transmitting .the movement of the armature 23 in a compound mannertoincrease its power, but in a straight line movement, there -is securedto one end of said armature 23 a connector rod 33, which passes througha hole in the end of the vibrator 34, and which is soldered therein.

Said vibrator 34; is of resilient material and has its rear end bent toform a spring which is secured by the screw 35 to the upper adjustablepole piece 29, and has secured thereto and adjacent to said rod 33 andparallel therewith a driver pin 36 the outer end of which may beconnected to the apex of a cone speaker in the usual manner, and

which may be of any suitable length.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent, is 2- 1. In a device of the class described, a

magpet, a'f pair of permanent pole pieces carr ed by said magnet, a pairof coil spacers havingone end rl'i'dly'attached to one of saidpii'iiianent poe pieces and the other end adjustably secured to theother permanent pole piece, said coil spacers formed with aliuedbearings, an armature mounting adjustably mounted therein and meansmeansfor transmitting movement from said armature. p

2. In a device of the class described, and in combination with a magnet,of a pair of permanent pole pieces carried thereby and in parallelrelation with each other, a pair of L-shaped coil spacers having one oftheir ends secured at right angles to said permanent pole pieces, andthe other end adjustably secured in abutting relation to the otherpermanent polecpiece, a pair of U-shaped adjustable pole pieces mountedin alined relation with. each other and at right angles to saidpermanent polepieces and held in an adjustable manner between theabutting ends of said permanent pole pieces and said coil acers, saidcoil spacers formed with alined 0 amp bearings, a pair of axial alincdplugs mounted therein inan adjustable manner, an armature her having itsends rigidly secured in said plugs, an armature secured at right anglesto said bar, and a pair of actuating COIlS surrounding each end of saidarmature and contained within tlie coil space and in spaced relationwith each other.

3. Ina device of 'the class described, and in commnation with a magnet,of a pair of permanept pole pieces having one of their ends secure tosaid magnet a pair of L- shaped coil spacers having t eir body portionsecured at right angles to one of said permanent pole pieces and theirfoot portion secured in an adjustable manner to the end of the otherpermanent pole piece, coil spacing pins secured to the body ortion ofsaid coil spacers on the same vertical plane, said coil spacers formedwith an al ned bearing, an armature, an armature bar secured at rightangles therewith and having its ends mounted in said bearin s, means foradjustmg said bar in saidearings, means for clamping said bar in saidbearings, a pair- 4. A speaker unit of the class described,

comprising a magnet, a pair of permanent pole pieces, one placed abovesaid magnet and the other below said magnet with their rear ends securedthereto, a pair of L-shaped non-magnetic coil spacers having one oftheir ends rigidly secured to and at right angles to one of saidpermanent pole pieces, and their other ends secured in clamping relationwith the other permanent pole piece forming a coil space, a pair oflaminated pole pieces mounted in the same vertical plane and held inadjustable and clamped relation by said permanent pole pieces and saidcoil spacers, said non-magnetic coil spacers formed with an alinedbearing and a saw-cut portion connecting therewith, a pair of plugsslidably and rotatably mounted in said bearings, and means for clampingthe same therein, an armature bar carried by said plugs, anarnmtureisecured at right angles to said bar and in spaced relation withthe ends of said adjustable pole pieces, and means for adjusting the airgap between said pole pieces and said armature, coils .mounted withinsaid coil space and surrounding said armature, and means fortransmltting vibrations trom said armature.

5. A speaker unit of the class described, comprising in combination witha permanent magnet, of a pair of permanent pole pieces having their rearends secured to the ends of said magnet, a pair of non-magnetic spacershaving one of their ends attached at right angles to one of saidpermanent/ pole pieces and the other end adjustably secured to the otherpermanent pole piece, a pair of adjustable pole pieces secured to theends of said permanent pole pieces at right angles therewith and on thesame vertical plane with their ends in spaced relation with each other,an armature mounted in the same vertical plane as said adjustable polepieces and in spaced relation thereto, means for adjusting saidspacedrelation between said pole pieces and between said pole pieces andsaid armature, and means for locking said adjustment, and a pair ofcoils mounted in the field of said magnet and said pole pieces.

In testimony whereof I. hereunto aflix my signature.

OTTO S. DRAKE.

